In a series connection, resistors are sequentially linked, and the same current must flow through each. The voltage across these resistors can be expressed using Ohm's law. According to Kirchhoff's voltage law, the sum of the voltage across the resistors equals the source voltage. As a result, the current in the circuit equals the source voltage divided by the total resistance in series. Substituting the current expression in Ohm's law gives the voltage across each resistor. So, the source voltage is divided proportionally among multiple resistors according to their individual resistances, which is known as the principle of 'voltage division.' A circuit that demonstrates this principle is called a voltage divider. A combination of resistors in series can be treated as a single equivalent resistor. The resistance of this equivalent resistor equals the sum of the resistances of the individual resistors in series. The equivalent resistance can be generalized for any number of resistors connected in series. Similarly, a generalized expression for voltage drop across these resistors can be written.